Inconsistent evolution and growth-survival tradeoffs in Gambusia affinis.

Area of Science:

• Evolutionary biology
• Ecology
• Animal behavior

Background:

• Growth-survival tradeoffs are hypothesized as a general mechanism driving prey evolution.
• Understanding these tradeoffs is crucial for predicting evolutionary trajectories.

Purpose of the Study:

• To investigate the evolutionary contributions to growth and survival in western mosquitofish (Gambusia affinis).
• To assess the consistency of evolved growth and survival across populations from different predation environments.
• To determine if a growth-survival tradeoff exists at the population level.

Main Methods:

• Common-reared western mosquitofish from 10 populations with high- and low-predation histories were used.
• Growth and survival rates were measured in controlled pond mesocosm experiments.

Main Results:

• Evolution of growth was consistent: fish from low-predation environments exhibited higher growth.
• Evolution of survival was inconsistent across populations, showing divergence unrelated to ancestral predation.
• The inconsistency in survival evolution precluded a population-level growth-survival tradeoff.

Conclusions:

• The generalizability of contemporary evolution depends on the local context of evolutionary tradeoffs.
• Focusing solely on singular selective agents like predators without considering local context limits insights into broad evolutionary patterns.